Control for concrete mixers and the like



Aug 22, 1950 A. MGMILLAN ETAL CONTROL FOR concmm: uixERs AND THE 1m:

10 Sheets-Sheet 1 Filed Kay 26, 1947 if. VIAILL A. E. MILLEE? 21?. 153GQHTER INVENTGRfi M z a g- 1950 A. MOMILLAN ETAL 2,519,391

CONTROL FOR CONCRETE MIXERS AND THE LIKE Filed May 26, 1947 10Sheets$heet 2 g 9 1950 A. MCMILLAN ETAL 2,519,391

comm. FOR CONCRETE MIXERS AND THE LIKE Filed May 26, 1947 10Sheets-Sheet 3 A. NM/LLAN 6.1!. V/ALL A.E. MILLER /8 63.0.6ARFERINVENTORS ATTORNEY g- 1950 A. MCMILLAN EI'AL I 2,519,391

CONTROL FOR CONCRETE uzxms AND THE LIKE Filed May 26, 1947 10Sheets-Sheet 4 1 a 3 8, Q N Q 1 DISCHARGE 8 N) g \z k Q I TRANS. OPEN \9k 3 g TRANS. CLOSED r5 3 k a; b k g SKIP up a g i INTERRUPTER 1 WATEROPEN Q I Q n :2 WATER CLOSED N g b i a) FE\\\\\\ J & gil- \NSB/ L Jggg mA I I I i o q i l x Q kg 2 Q o m ET is Q & & 1 .-s= W E N r, \Q I K\ 1 &I" N w o m Q K N w 0 k no '0 \a \o w K i? Q :t

A. uw/LLA/v a. x. WALL A. E. MILLER Li I 6.0. CARTER INVENTORS by AQMATTORNEY Aug. 22, 1950 A. MOMILLAN EI'AL 2,519,391

comer. FOR CONCRETE MIXERS AND THE LIKE Filed llay 26, 1947 1oShet's-Sheet 5 A. MMILLAN G. K. WALL A. E MILLER G. D CARTER INVENTORSATTORNEY g- 1950 A. MCMILLAN EI'AL 2,519,391

CONTROL FOR CONCRETE MIXERS AND THE LIKE Filed May 26, 1947 10Sheets-Sheet 6 Fig, 60

' /u'//////////////////4 /l/l/l/l/ll/ll/I/l/l/VIII/ll 04 A. uw/LLA/v Ia. K. WALL A. E. MILLER [0-4 6.0. CARTER INVENTORS ATTORNEY g- 1950 A.MCMILLAN ETAL CONTROL FOR CONCRETE MIXERS AND THE LIKE 10 Sheets-Sheet 7Filed May 26, 1947 A. MM/LLAN 6. K. WALL A. E. MILLER 6. D. CARTERINVENTORS ATTORNEY Aug. 22, 1950 A. MCMILLAN ETAL CONTROL FOR' CONCRETEMIXERS AND THE LIKE l0 Sheets-Sheet 8 Filed llay 26, 1947 INVENTORS Mn m#7 Aug. 22, 1950 A. MCMILLAN ETAL CONTROL FOR CONCRETE MIXERS AND THELIKE l0 Sheets-Sheet 9 Filed May 26, 1947 A. MM/LLAN G. K. V/ALL A. E.MILLER 6. 0. CARTER INVENTORS BY /%z M ATTORNEY 1950 A. MQMILLAN ETAL2,51

CONTROL FOR CONCRETE MIXERS AND THE LIKE Filed May 26, 1947 10SheetsSheet 10 A.E. MILLER 6.0. CARTER INVEN TORS y ATTORNEY PatentedAug. 22, 1950 OFFICE Andrew McMillan, Milwaukee, George K. Viall,Shorewood, Arthur E. Miller, Whitefish Bay, and Gerald D. Carter,Milwaukee, Wis., assignors to Chain Belt Company, Milwaukee, Wis., acorporation of Wisconsin Application May 26, 1847, Serial No. 750,544

17 Claims. (Cl. 259-163) U This invention relates to controls forinitiating in timed sequence and in novel manner various operationswhich are repeated in the cycle of operation of a batch mixing machine.

For a number of years emphasis in development of concrete mixers ,forroad paving work has been to increase output while maintaining andimproving the quality and uniformity of mixing. To this end, pavingdrums have been employed utilizing two compartments arranged to mix insequence the batch of materials passing through the drum. Sucharrangements produce considerable time saving because in effect twobatches, rather than one, are being mixed at a time. The sequentialarrangement of the compartments in actuality results in apartial mix ofeach batch in each of the compartments. By providing a transfermechanism between the compartments which prevents transfer while thefirst compartment is being charged, and also until the secondcompartment is discharged, the principle of batch operation ascontrasted with continuous operation is preserved, i. e., regulatedquantities of materials comprising each batch can be mixed for adefinite interval of time and uniformity of quantity and quality of theseparate batches can be consistently maintained.

These advantages of two compartment mixing drums are well known in theart and automatic mechanismhas been provided to relieve the operator ofthe difficulty of manually having to initiate each of the operations ofthese relatively high speed machines. By providing automatic means toinitiate those functions that are normally non-varying in time sequence,losses in time and undesirable variations in timing are avoided.Moreover the operator is free to devote more attention toeontrollingrmanually the functions of a varying nature such as theplacing of concrete with the boom and bucket, the maneuverlng of themachine as paving of a given area of ground progresses, and the like.

The time required to mix a batch of concrete may vary considerably ondifferent Jobs; so also does the time required to discharge the drum andthe time to transfer the batch from one compartment to the other wheretwo compartment drums are employed. The differences in character of theaggregates, the quantity of water used and the presence of grades orhills are some of the principal factors which cause these variations.Automatic controls for machines which are moved from one job to another,wh re differences in mixing specifications and operat that adjustmentsto meet different mixing time requirements and job conditions may bemade in a much simpler, easier and more foolproof manner.

In two compartment paving drum operations, there are really two cyclesof operation involved, and for convenience these will be designated themixing cycle and the control cycle. The mixing cycle is the cycle whichis repeated at definite intervals during the function of the machine.and controls the actual period of time during which mixing occurs.-Normally, there is associated with the mixing cycle means for positivelypreventing discharge of the contents of the drum prior to completion ofa definite, predetermined period of time set by the engineeringspecifications for the job. The mixing cycle is normally inaugurated atthe moment when the drum is being charged with the concrete producingingredients.

The control cycle embraces a different period of time than the mixingcycle, as it embraces the cycle of the functions controlling theprogress of the batches through the drum. The control cycle may belonger or shorter than the mixing cycle, and these may be overlappingsince during the control cycle, not only does the mixing cycle or aportion of it occur, but also the additional operations of dischargingof the drum con-'- tents and charging of the drum. In some instances themixing cycle on two different jobs will remain constant, but the timerequired for these other operations which are part of the control cyclewill vary, and in order to get maximum output of the machine, thecontrol cycle must be capable of adjustment independently of the mixingconditions partment of the drum to the other, many specifi- 3 cationsinsist that the transfer time be excluded from the mixing time, andhence what is termed a penalty" is imposed on the machine. To meet suchsituations, the mixing cycle must be capable of further adjustmentsindependently of the cycle control, for obviously whether a "penalty" isimposed or not, the time for operation of the functions controlled bythe control cycle will not be affected thereby. The present inventionprovides improved means whereby such adjustments may be made.

In the present embodiment of the invention, the control cycle is startedjust after the completion of the mixing cycle. Hence before the mixingcycle is inaugurated, the drum must be discharged, and chargingmechanism, such as a skip brought to a charging position, and theingredients charged into the drum. The control cycle could, of course,be started at any time after completion of one mixing cycle, and priorto completion of the next, such for instance as the moment when thecharging mechanism is set in operation, in

. which event the cycle would run to a later period of time and includeas its last operation the functioning of the discharge device. Thepresent invention is not dependent upon where the control cycle starts,and is intended to cover broadly the correlation of functions ratherthan any particular cycle of operation.

It is desirable that each control cycle should be started manually andthis means that either the inauguration of charging or of dischar independing on where the cycle starts or ends, will take placeautomatically. There is some danger in this, for instance if the skip beset in upward motion automatically, that the loading trucks may not beremoved therefrom. Similarly, if the discharge function is automatic,the time required for suitable distribution of the batch by thedistributing means may be unduly restricted on account of the necessityof relatively quick return of the bucket to avoid deposition of a batchdirectly on the ground.

The present invention provides means for automatically interrupting theoperation of the control cycle just prior to the time when any suchoperation would if continued possibly produce an undesirable condition.and it further provides means whereby the cycle may be easily set backin operation once the operator is satisfied that it may safely proceed.Alternately if the operator does not want the cycle interrupted, he can,with the mechanism of the present invention, prevent its interruption,but it requires a positive act on his part, which is desirable from a.standpoint of ciiicient results, as well as a source of mental relief tothe operator.

The functioning of the automatic interrupter does not interfere with theproper timing of any subsequent functions in the control cycle, nor doesit aflect the mixing cycle adversely.

Other objects and advantages of the invention will manifest themselvesin the following detailed description and by reference to the accompany--ing drawings which illustrate a preferred embodiment of the variouscoacting elements and combinations.

In the drawings:

Fig. 1 is a side elevation of the paving machine showing the arrangementof the various instrumentalities subject to control functions;

riaflisanendviewofthecontrolboxand housing for the fluid valve actuatingmembers, with parts of the housing broken away;

Irina; 321s a front view of the mechanism shown Plg. 3a is a sectiontaken on line 84-80 of Fig. m 4isasectiontakenontheline4-4of 10 is asection taken on the line llll of Fig. 11 is a sectionltaken on the lineof 12 is a section taken on the line I2-l2 of Fig. 13 is a perspectiveview of the cams and clutch actuating levers for controlling the cyclecontrol and mixing control shafts;

Fig. 14 is a sectiontaken on the line "-44 of Fig. 4, showing the mixingcontrol actuating and stopping mechanism;

Fig. 15 is a perspective view of the planetary gear mechanism forcompensating the adjustment of the mixing control cycle in response toadjustment of the cycle control;

Fig. 16 is a side elevation of the cam and mechanism for starting andstopping the cycle control;

Fig. 17 is a section through the control box showing a modified form ofapparatus to produce a longer mixing cycle; and

Fig. 18 is a section taken on line iI-II of Fi 17.

For the purpose of illustration, the invention is shown in the drawingsas applied to a concrete mixer having a two-compartment drum, althoughit will be understood that many of its features can be utilized indifferent applications, for instance in one-compartment drums, orwherever automatic control of sequential operations produced by such amechanism is desirable.

General arrangement of operating functions The paving machine isillustrated generally in Fig. l, and comprises the drum ll mounted forrotation in a frame I! which is supported on crawler tracks I! thatpropel it along the ground. One end of the drum is provided with anopening ll through which materials elevated by the skip I! may becharged. Intermediate of the drum is a partition I, dividing it into twocompartments l1 and it of substantially the same size, the partition Ihaving a central opening adapted to be opened and closed by a transferdoor I! which may be moved axially of the drum. The construction of thetransfer mechanism and the partition form the subject matter of PatentNo. 2,434,218, granted January 6, 1948, on a copending applicationSerial Number 566,491, filed December 4, 1944, by Andrew McMillan, oneof the present applicants.

The door II is actuated by a mechanism II, which comprises bifurcatedmembers II in the region of the opening ll to permit the charging skipII to extend between them as it enters the opening I. For reciprocatingthe door I! and the mechanism 20 there is a plunger 22 of a hydraulicram II, one end of which is pivotally secured to the frame, and whenhydraulic fluid enters the ram, the door is moved to the left of thedrawing to permit transfer of the material from the first compartment llto the second compartment l3. Ram 23 is hydraulically operated in onedirection only, the door ll beingreturned when the hydraulic pressure isreleased to its closed position by springs 24 connected to the mechanism20. This mechanism comprises springs 24 which are mounted on the frameand which exert tension on a lever 23, pivotally suspended from theframe. The lever 23 is pinned intermediate its ends to the plunger ofthe ram 23, connection being made with the mechanism 29 by securing theupper end of the lever 28 to a shaft fromwhich depend the arms 23'.which are connected to the end of the yoke 2|.

The skip II is elevated by cable 26 secured near its outer end, thecable being trained over pulleys 21 and 28 to a pair of winding drums,which are driven in a conventional manner through a second cable thedriving end of which is wound on a drum 29 journailed on a power shaft30; the latter is driven by the power plant of the machine. Aconventional clutch 3| with interlocked brake controls the skip andcauses the shaft 33 to drive the winding drum 23, the clutch 3| beingshifted by a lever 32 which is actuated in one direction by thehydraulic ram 33, shown in the extended or engaged position in Fig. 1,and in the other direction by the hydraulic ram 34. The clutch 3! is ofthe type that once it is shifted into engagement by the ram 33, it willstay engaged, and disengagement is ordinarily eifected by an automaticmechanical knockout of well known construction actuated by the skip atthe end of its travel. The cylinder 34 is available merely to permit theoperator to disengage the skip clutch if desired prior to itsdisengagement by the mechanical knockout. The ram 33 is spring loaded sothat when fluid pressure is shut oil from the source of fluid power, thespringwill return the ram to its original position by forcing the oilback through the pipe which serves it. This takes the ram out of the wayof clutch lever 32 so that full disengagement is assured when either theram 34 or the mechanical knockout operates.

Water is introduced into the first compartment ll of the drumconcurrently with charging operations, a water tank 35 being suitablylocated adjacent the charging opening to store and discharge.

the requisite amount of water for each batch of concrete. Theconstruction of the valves and piping leading to and from the tank 35are not disclosed, but reference may be had to U. 8. Patent No.2,280,518 to C. F. Ball which discloses a mechanism suitable for this.purpose. In that patent, a single cable connected to the controlinstrumentalities of the machine operates valve mechanism which permitswater to flow first into the measuring tank and then, during a differentinterval of time, permits the desired amount of water to flow from thetank to the drum. In lieu of the cable shown in the aforesaid Ballpatent, the present invention provides a hydraulic ram 36 suspended fromthe frame and arranged to overcome the spring loading of the valvemechanism generally designated 31 which may function in accordance withthe Ball patent men- 6 38, which maybe of well known construction. saidchute being arranged when in the position shown in Pig. 1 to receive themixed concrete elevated by the blades in the final compartment and thento deliver such concrete through the opening 39 at the discharge end ofthe drum. The chute 33- is pivoted at 49 on the frame l2 and maybeshifted to a position where it is wholly removed from the drum. inwhich event no material will be discharged. To move the chute betweenthese positions, hydraulic ram 4i mounted on the frame actuates an arm42 which is linked to the chute, the ram being positively operated ineach direction by fluid pressure, as hereinafter described.

Concrete discharged from the chute 33 is received in. a bucket 43 whichis caused to traverse the boom 44 permitting it to be deposited in thedesired position on the roadway. The bucket distributing mechanism andthe means for controlling it are not shown as they form no part of thisinvention. Reference may be had to Bali and Hilkemeier Patents Nos.2,284,- 249 and 2,295,509 for disclosure of suitable elements to performthese functions. It might be mentioned, however, that the bucket iscaused to travel on the boom by engagement of a clutch in a gear casedesignated 45 which is mounted near the operator's position, and thatthe drive shaft for this mechanism, which is constantly running whilethe machine is in operation, is employed to drive the controlinstrumentalities {:r the hydraulic elements hereinbefore referred Thevarious hydraulic rams are all operated from a fluid control box 46,which is equipped with a plurality of hydraulic valves controlling theflow of fluid to the various actuating rams which have been described inconjunction with the major operating functions subject to their control.A fluid reservoir 41 communicates through a line 48 to the pump 49 andthe latter through a line 50 to the fluid control box.

tioned in this paragraph. The means for controllingthe operation of thevalve mechanism,

Fluid pressure is constantly available in the box and by movement of theappropriate valves, as illustrated in Fig. 1, this pressure can be putin communication with any of the following lines: the line 5| whichtransmits fluid to actuate the ram 4| to remove the chute from the drumand prevent discharge; the line 52 which transmits fluid to the ram 33which engages the skip clutch; the line 53 which transmits fluid to theram 34 to disengage the skip clutch, if desired, at any time prior tothe auto- 7 matic disengagement caused by the elevation of the skip tofully raised position; the line 54 which transmits fluid to the ram 23to open the transfer door l9 and maintain it in open position for apredetermined-time; the line 55 which transmits pressure to the ram 36to thereby open the water valve leading from the tank 35 to the mixerdrum and maintains it open for the desired period of time; and the line56 which transmits pressure to the outer end of the ram 4| in order tocause the chute 33 to be returned into the drum to permit discharge ofthe mixed concrete.

The same hydraulic valves control the lines 52 and 53 and the lines 5iand 56 respectively, and as a result there are four control valvesinvolved in the present embodiment of the invention. In the drawings, afifth valve and-operating lever are illustrated, but the latter are forthe purpose of operating the rams which control the clutches for the twocrawler track 7 drives, and form no part of the present invention.

The construction of the valves and their system of communication withthe fluid in the fluid control box are not illustrated as variousconventional valves may be employed and no particular one is requisiteto this invention. The

The control boa:

To obtain the desired time sequence of operation of the varioushydraulic rams and likewise, and equally important, to obtain thenecessary time dwell in their respective operations, two mechanicalcontrol instrumentalities are employed, one which is designated as themix control" and the other, the cycle control." These controls arelocated in enclosedboxes or cases below the gear case 40 and above thefluid control box 06, and the valves in the latter are operativelyconnected to the mechanism in these two boxes.

Power for operating the mechanical controls is derived from the buckettravel Sear case 00, as previously mentioned, and as illustrated inFigs. 2 and 3, a chain is employed to transmit rotary motion from saidpower source to a sprocket 59 mounted on a shaft 00 which enters theback of the mix control box 0|. An adjustable idler shoe 02 maintainsthe chain 00 under proper tautness. A pinion 00 at the inner end of theshaft 60 drives a bevel gear 00 mounted on a shaft 65, as illustrated inFig. 4. A sprocket 00 secured to the end of the shaft 00 drives a chain01 which is trained around a sprocket 00 Journalled on a countershaft09. The sprocket 00 is integral with a pinion 10 which meshes with gearsII and 12 journalled respectively on tubular shafts l0 and 10. The shaft10 extends through the full length of the mix control box 0| and theshaft 14, which is somewhat longer because it carries more controlinstrumental ities, extends through the full length of the cycle controlbox designated 15. The mix control box 0i is bolted or otherwiseremovably secured to the cycle control box I and the two boxes have opencommunication between them to permit interaction of parts as will besubsequently described.

Clutches IS and 11 are slidably keyed to the hubs of the gears I2 and IIrespectively and are arranged, when shifted, so that their clutch teethmay positively engage the respective teeth on discs 10 and 00 which arefixedly keyed to the shafts l4 and I3;

The clutch I0 as shown in Fig. 13, is actuated by a shifter arm 0|mounted on a vertical sleeve 02, journalled on shaft 02', which sleevehas an arm 00 connected to a rod 00 extending through the front of thebox 15, the outer end of which is pinned as shown in Fig. 2, to a handlever 00 journalled on a bracket 00 extending from the box. By movementof the knob 01 toward the left as viewed in Fig. 2, the clutch 10 causesthe shaft I4 to rotate and starts into operation the cycle control.

The cycle interrupter Mounted on the shaft I0 are a plurality of cams.each of which will be descibed separately,

for controlling various functions. One of the cams (see Fig. 13) is thatdesignated 00 which engages a follower roller mounted on an arm 00 of abell crank 0|, journalled in bracket 00; the other arm 02 of which ispin-connected to a sleeve 00 enclosing an extended part of the rod 00previously mentioned. A spring 00, surrounding the rod 00 and adiustablycompressed by a nut 00 threaded on the end of the rod, transmits forceapplied by the cam 00 to move the rod 00 and thereby disengage theclutch 10, by overcoming the initial compression of and by furthercompressing the spring I00, as hereinafter described.

The purpose of this automatic interruption of operation is to enable theoperator to assure himself that the skip is clear of any trucks or otherobstruction; and that the cycle may safely proceed. It relieves him ofthe responsibility of having to manually interrupt operations should itbe unsafe for the skip to be elevated. If he is satisfied before thisautomatic interruption occurs that the cycle may proceed withoutinterruption, he may, by holding the knob 01 momentarily in an inwardposition, prevent the automatic disengagement of the cycle controlclutch, for the spring 00 may be compressed sufllciently to let thefollower 00 ride over the cam 00. Should the cycle be interrupted,however, all the operator has to do is to push the knob 01 inward andthe clutch I0 is immediately re-engag'ed to resume the cycle. A locklever 00 mounted on shaft 00 (see Figs. 2, 3 and 3a) is journalled onthe bracket 00 and has an engaging surface 00" which may be moved, ifdesired. to the dotted line position shown in Figs. 2 and 3a to maintainthe lever 00 in the outward position, insuring that the clutch 10remains disengaged.

I Cycle control operations To initiate the elevation of the skip byactuating the hydraulic control valve for ram 00, a cam 01 (see Figs. 4and 6) driven by the cycle control shaft 10 is arranged to engage aroller 00 (see Figs. 7, 10 and 11) on a follower arm 00 disposed to therear of said shaft and journalled indirectly on the cam follower shaftI00. Also journalled indirectly on the shaft I00 is a member IOIcarrying an arm I02; the outer extremity of arm I02 is pinned to the rodI00 (see Fig. 3) which reciprocates the valve that controls the flow offluid to the skip actuating clutch ram. Arms 00 and IN are yieldablyconnected by a compression spring I00 encircling a bolt I 00 whichextends through apertures in ears extending from the arms. Suflicientinitial compression is imposed on the spring, such that movement of thecam follower arm 00 by the cam will not cause further compression, butwill move the member IN and its actuating arm I02 through the same angleas the arm 09. Also linked to the rod I00 is a bell crank I00 Journalledon a shaft I01 which is parallel to the shafts l0 and I00, but isoutside the case I0. The upper arm of the bell crank I00 is providedwith a knob I00, permitting the operator to operate manually thehydraulic valve. Thus knob I00 is unyieldably linked fo its hydrauliccontrol valve, so that by holding the knob I00 firmly, the operator mayprevent the skip clutch from being engaged, for

moving the knob toward him and'awa'y fromthe cycle box,i-: shift the'val'v'e to itsopl'iosite' extreme positionto 'f-open communicationibetwee'm the fluid pump and the line' SIE whereby-the ram 36 willdisengage the :skip clutch and rprevent v.i'urthermelevation of-'"'theskip; Proper relationship f 51 between the cam 1 and -valve: istsecuredthrough adjustment mean's provided on rodllllw l I The hydraulic valve'forfoperatingskip clutch rams 33 and 34 is of the fiopen-"centefl'type,

in central position of1the valve," both rams are in communication: with:the no' pressure" line 5-1. When'opened by cam :fli-Jfluid pressure isimposed: on i the lram i 33' rfor the timei necessary to complete" itsmotion and cause engagement of I theskipclutchgr M v The camfolloweraconstruction forvactuating the valveziwhich controls? thefautomatic return of the discharge: chutetench-discharging position :issimilar to 1 that just described: for actuating the valve which: causesskip clutch :engagement.- In this'casa-the cam IIII acts upon followerarm Illflwhich-is disposed forwardly-of the shaft 14 (see Fig. 6)andisyieldably connected through a compression spring, which functionsexactly as thespring-IIILtoanarm l H which isisecured tothe shaftllIlI,*-the"=1atter shaftcarrying an arm I I2,.- which :is'pinned tothe. valve rod I I3 which actuatesthevalve admitting fluid through thepipe 5|; to the discharge'chute ram II. The

knob: I ll which is at the end of the bellcrank- H5 that connects to therod. H3 may be employed. similarly to the 'knob- I63, to manually causesuch operation, or to prevent cam actuation, or to reverse itheposition'of the chute caused by cam actuation,iwhichever is' desired,

in operation, but the'means for moving the chute I to discharge positionis manually operated.

The hydraulic valve for the discharge chute is of. the closed-center"type, which locks the chutewhenthe valve is in neutral. Shifting toeither side causes fluid'actuation of which operates the chute.

The hydraulic valves for controlling fluid to actuate the rains"associated with the transfer door and the water valves are also. ofclosedcenter construction. vWhen shifted to one posithe ram tion by the,cams that operate them they impose fluid pressure on the rams theycontrol to cause their extension and to maintain them in extendedposition when the valves are returned to neutral. After the requiredtime interval, these valves are shifted in theeopposite direction byautomatic means, causing their fluid supply lines to connect with"no-pressure line 51 and-"permitting the springs associated with therams to return the rams to their original positions. However, two camsareeniployed for each of these valves,"as the ramsare' operatedautomatically in both directions, rather than automatically in onedirection only, as in'the case of the skip "clutch and the dischargecontrol valves. Th

followers for each pair of cams, as shown in Figs. 8 and 9, are linkedtogether so that a single operating lever may be employed to actuateeach of the' valves.

{Thecam 6 for opening the transfer door is arranged to engage thefollower III which is rearwardly of the shaft I4 and isindirectlyllournalled on the shaft I00. Follower III hasfan abutment 6-extending from its hub which butts a ainsta stop II! extending from a'sleeve, I20. e sleeve I2l carries the arm I2I that actuates the rod I22which is connected to the fluid valve controlling the movement of thetransfer door. Cam I23, which is set relativegsto opening cam II6 "toprovide the desired time interval between opening and closing of thetransfer door, is arranged to actuate the follower arm lu which has anabutment I26 arranged t9 n a e the stop II! on the opposite side fromthat engaged by the abutment II8 on the arm I I'l The two arms I I1 andI24 are normally moved together, a compression spring I26 being betweenears mounted on said arms, the spring being held in place by a bolt I21which extends through aligned apertures in the aforesaidears. Thus whenthe cam II6 engages the follower on the arm I" to move the latter in a:counterclockwise direction as viewed in Fig. 8, the spring transferssuch movement to the follower,l2l and the abutment I26 engages thefinger H3 andthrough sleeve II9' rotates the arm I2I to effect openingof the door. The valve is maintained in this position by the cam II6until the required time for the opening of the transfer door to becompleted, whereupon rotation carries the lobe of the cam beyond thefollower and permits the valve to return to neutral, leaving the ram 23hydraulically locked in the door-open position. After the proper timeinterval to allow transfer of the batch, cam I23 acts to move thehydraulic valve from neutral in the opposite direction, putting the ramin communication with no-pressure" line 61 which permits springs 24 tocollapse the ram and close the door. Action of cam I 23 engages thefollower on the arm I24 and moves it in a clockwise direction whereupon,through the spring I26, engagement with the abutment H8 rotates the armsII! and I2l to move the rod I22 downwardly, thereby moving the valve inthe opposite direction to that imposed by cam I I6.

Spring I26 is pre-loaded and acts in the same manner as spring I;normally the cam follower will move the arm I2I, and'yet the spring I26permits the arm I2I to be moved independently regardless of therelationship that may be obtained at any moment between cams H6 and I2;and their respectiveflfollowersw In addition, spring I26 permits bothcams to act simultaneously, if by inadvertence this were to happen(through some maladjustment), without causing undue strain or breakagebecause of such opposing movements.

' For controlling the movement of the water valves, the shaft I4 carriescams I30 and I3I, best illustrated in Fig. 12, cam serving to causeintroduction of water into the mixer drum I1 and cam I3I to restore thewater valves to their original position to refill the tank. The camfollowers I32 and I33 which are associated with the cams I30 and I!respectively, have abutments extending from their hubs and are linkedtogether by spring connecting means in the same manner as the followerarms that actuate the valve controlling the transfer door. Similarly, afinger I55 (see Fig. '1) which engages the lever abutments extends fromthe sleeve I55 which is journalled on shaft I III and can'ies the armIll. The arm I" actuates the rod I55 which is connected to the fluidvalve controlling the movement of the water valves. Rod I" is linked toa bell crank I51 carrying the knob I55 permitting manual operation of,or manual prevention of the automatic operation of the fiuid controlvalve.

The mix control To start the mix control shaft 13 into operation,

illustrated in Figs. 13 and 14, the cycle control shaft 15 carries a camI35 arranged at the proper time interval to actuate a follower arm Iwhich is pinned at its lower extremity to the housing of the box 15. Theupper extremity of arm I" is apertured to accommodate a bolt III whichoperates, through an overtravel compression spring I52, the shifter armI45 to engage the clutch 11 on the mix control shaft 13. To securecondign relationshipbetween cam its and clutch 11, spacing of theshifter arm I55 from the arm I45 is adjusted by the setscrew I45 whichis threaded through the arm I40 and bears against the shifter arm I, tolimit bias of spring I42. The cam follower is maintained in engagementwith the cam by the tension spring I 55.

The shifter arm I45 is mounted on a sleeve I41, iournalled on a shaftI41 which is in substantial vertical alignment with the shaft 82' whichjournals the shifter for the clutch 16 of the cycle control shaft.Shifter arms I" are also mounted on sleeve I41, which construction is aduplicate of shifter arms mounted on sleeve 52, and when shifted theclutch teeth 18 on the clutch 11 positively engage the respective teethon disc 50 and cause the shaft 13 to rotate. Shaft carries a cam I45 asillustrated in Fig. 12, which engages a plunger I50 and causes the bellI5I on the top of the case 6| to be chimed at the proper time interval.Shaft 15 also carries a cam I52 which maintains a plunger I53 inposition to prevent manual operation of the discharge chute lever II 5to cause dischar e prior to completion of the mixing cycle. To this end,the lever II5 carries an ear H5 disposed in the path of the plunger I53.The plunger I53 extends through an opening in the front of the case 15and is tensionecl against the action of the cam by a spring I54 which issecured to a stirrup I55 mounted on the plunger. The upstanding arms ofthe stirrup carry a pin I55 arranged to abut the cam I52 when the lattermoves into operating position. The land of cam I52 has a bevelledportion I52 on its trailing side to permit the spring I55 to begin toretract the plunger I55 at a time somewhat before the unlocking of thelever I I5. This preliminary movement of the plunger I53 notifies theoperator of the approach of completion of the mixing cycle, and tends toeliminate the human reaction time lag, for the operator will either keephis hand on the lever H5 and feel this preliminary release. or he willobserve the movement of the plunger and then place his hand on the leverbefore complete release occurs. Upon complete release of the lever bythe plunger, the operator may shift the lever inwardly and causeoperation of the hydraulic ram II, which produces movement of the chute35 to discharge position to initiate discharge of the contents of thesecond compartment of the drum.

If desired, the cams I55 and I52 may be adjusted with respect to eachother so that plunger I 55 may be fully retracted to permit movement oflever I I5 slightly in advance of the release of the plunger In thatproduces ringing of the bell III at the completion of the mixing cycle.The amount of this advance setting will correspond to, but not exceed,the time required for the chute 55 to move from its out or non-dischargeposition through the first part of its motion toward the in or dischargeposition, so that actual discharge of the batch is inauguratedimmediately and without any time lag, upon completion of the mixingcycle. The actual time required for the chute to move through thenon-effective part of its travel may be of the order of slightly lessthan Y a second, but when it is considered that the batches are producedat the rate, in many instances, of about one every 35 to 40 seconds, thecumulative effect of this time saving over the course of a day is amajor advantage.

The cam I45 carries a pin I51 extending laterally therefrom, which uponeach revolution of the cam trips an arm I55 that actuates a revolutionrecorder I59 to indicate the number of batches mixed in the machine.Neither the recorder nor the bell ill need be described as they are wellknown mechanisms such as have been used for many years.

The operation of the cam I5I which serves to move the fluid valve torestore the water control valves to the tank refilling position, aspreviously described, is effected by a sprocket I55, carried by theshaft 13, said sprocket driving a chain "I trained over a sprocket I52mounted on the hub I63 (see Fig. 4) which carries the cam I5I. This isdone merely because the time for performance of this function is aftercompletion of the cycle operated by the shaft 15, the mixing cyclecontrolled by the shaft 15 being still in operation, whereby power isavailable to perform this function.

Disengagement of driving clutches for cycle control and mi: controlshafts As previously described, the clutch 1' which drives the cyclecontrol shaft 14 is manually engaged, by operation of the hand lever 55,to start the control cycle. By operation of the lever 55, the clutch mayalso be disengaged at will, either prior to or subsequent to theoperation of the automatic interrupter mechanism 85, 89, etc. As aresult, there is provided a manually operable, over-all control forcycle functions which is in addition to the optional manual control foreach of the functions.

When the shaft 14 has made a complete revolution, theroller I55 on thearm I55 (see Figs. 13 and 16) is urged into a notch I51 in the cam I N,a tension spring I55 connected near to the upper extremity of the armI55 being employed for this purpose. Movement of the arm I55 inwardly ofthe cam exerts force through the setscrew it! which bears against thearm I10 extending from the upper portion of the shifter sleeve 52. Thusas the follower drops into the notch I51, the clutch 15 is disengaged.

There is an identical mechanism for disen gaging the clutch 11 whichcontrols the drive of the box. and the arm I12 is held under tensionnear to its upper extremity, The arm I12 is operatively connected to theshifter arm I15 which extends from the sleeve I41, and as the followerdrops into the notch in the cam III, the sleeve I41 is rocked to shiftthe clutch fork I48 and disengage the clutch 11. Arm I12 is connected tothe shifter arm I15 by over-travel compression spring I16 whichsurrounds a bolt I11 extending through apertures in the arms I12 andI15. A setscrew I18 threaded through the bias of the spring I16. Thenuts I18 threaded on the end of the bolt I11 permit proper initialcompression to be exerted on the spring I18.

In the case of disengagement of the clutch for the cycle control shaft14, there is an identical compression spring I88 adjusted by nuts ill(see Fig. 16). Spring I88 in addition to permitting over-travel, as doesthe spring I16, permits the clutch 16 on the shaft 14 to be disengagedby the interrupter mechanism 88, 88, etc., or manually at any time,while the roller I66 is riding on the surface of the cam I64 during thelatters cycle. Were it not for this yieldable connection employing thecompression spring I88, the shifter 8| could not be moved when thefollower was out of the notch I61 because the arm I65 cannot moveinwardly toward the cam. l

Adjustment of cycle control In the normal cycle of operations, upon theringing of the bell indicating the completion of the mixing cycle, theoperator will press the knob 4 toward the case thereby actuating thefluid valve to cause the discharge chute to be moved to dischargeposition; simultaneously therewith, he will press the knob 81 toward thecase to set in motion the cycle control shaft 14. Considering for themoment only the discharge function, it is desirable to be able to varythe duration thereof because, on different jobs, 'the time required todischarge may vary as-much" as 20% or more depending upon the harshnessor wetness of themix, the tilt of the machine, or

tegrally secured to the shaft 14. By providing a.

plurality of angularly spaced holes in the periphery of the arm I86, theangular relation of the parts may be adjusted and the setscrew I81 whichconnects them may be engaged with whichever hole in the arm I86 thatproduces the desired setting. A dial strip I88, best illustrated in Fig.5, mounted on the outer side of the arm I86 indicates which way torotate the plate I85 and thereby the cam II8 relative to the shaft 14 toincrease or decrease the discharge time, and may, if desired, hegraduated to indicate the exact period of time allotted for thisfunction. In practice only three positions have been found necessary,and these are long" and "short," and an intermediate position, asindicated in Fig. 5. Transfer from the first compartment of the drum tothe second compartment should be deniits adjustment of the position ofthe cam to e chute is in discharge the'only partially mixed layed whilethe position, for otherwcilfi batch which is diately start to discharge,and as a result if the period of discharge is varied, the time whentransfer is to commence should also be correspondingly varied. Hence thecaml It-which effects movement of the transfer door to transfer positionis mounted on the same sleeve I84 as the cam I I8, and any adjustment ofthe setting of one cam by the mechanism I85 and I81 will cause the samecorresponding adjustment in the setting of the other cam.

If the setting of the cam I I6 which inaugurates transfer is adjusted,the cam I28 which effects termination of transfer should becorrespondingly delayedv or advanced; and in addition, the latter shouldbe capable of separate adjustment as well, to aiford additional orshorter time to eflect the transfer operation. To accomplish theseadjustments, the cam I28 is mounted on a sleeve I88 journalled on theshaft 14, the sleeve I88 carrying adjacent its outer end an integrallysecured'flnger I88, the outer extremity of which is apertured toaccommodate a setscrew I8I by which the finger may be connected to theplate I85 that is associated with the cam II8. A plu-- rality ofangularly spaced tapped holes in the plate I85,v set on the oppositeside of the plate from the tapped hole engaged by the setscrew I81,permits the finger I88 to be angularly adjusted and locked by thesetscrew I8 I after which the cam I28 will be driven by the shaft 14through plate I85, the finger I88 and the sleeve I88 on which it ismounted. The dial strip I82, mounted on plate I85 carries suitableindicia, such as "long" and short, to indicate the di rection the fingerI88 should be rotated to increase or decrease transfer time.

Frd'm the foregoing it will be appreciated that adjustment of the plateI85 which adjusts the setting of the cam II8 for-inaugurating transferwill automatically adjust, to the same extent, the cam I28 which effectstermination of transfer. The tr ansfer time may be. separately adjusted,however, without affecting thedischarge time by inserting the setscrewI8I in different a pertures in the plate I85, a dial strip I82 mountedon the plate I85 indicating to the operator which'way to move the-fingerI88 to increase or decrease the transfer time. 7

.The period of time required to' elevate :the skip after the skip clutchis engaged does not vary, nor is there any material variation in thetime required to charge the drum once the skip is.

elevated. but this time should be dependent on the closing of thetransfer door to prevent entrance of the incoming material into thesecond of the two compartments of the drum. Hence the cam 81which-inaugurates skip engagement is mounted on the same sleeve I88 asthe cam I28 which effects closure of the transfer door, and skip clutchengagement is timed just sufficiently in advance of transfer closure topermit charging to commence practically simultaneously with transferclosing.

The cam I 88 for effecting water introduction into the drum is normallyin direct timed relation to movement of the skip. but occasionally itmay be desirable to set the cam I88 more or less in advance of the skipsreaching its fully raised position. Accordingly cam I38 is journalled onthe sleeve I88, and a lock nut I88 threaded on the sleeve and bearingagainst the cam I88 pererred may almost imme- '1! correspond -"to thenumbered notches on the sleeve I indicatim the number of seconds thewater valve is opened prior to the ship's reaching the end of its upwardtravel.

Adjustment of the mix control To increase or decrease the mixing time.the cam Ill which causes the bell to ring and the cam III, whichprevents premature discharge, may be adjusted relative to the mixcontrol shaft It by rotating the sleeve I on which these cams aremounted (see Figs. 4 and 5). The sleeve ill extends through the case IIand carries, outside the case. a handwheel i to which there is secured agear Ill arranged to mesh with a pinion Ill. The pinion I" is keyed to ashaft in extending through a disc I" keyed or otherwise secured to theshaft ll. The shaft I" is threaded at the end extending beyond the outersideofthedisclflandawingnutlllis threaded on the shaft to lock thepinion against rotation relative to the disc I" and thereby fix the camsin various radial relationships to the shaft II. no adjust the settingof the cams, the wing nut is loosened to permit pinion It! torotatefreely and the handwheel i" turned relativeto the disc m, a dialin imounted on the dhc I indicating, preferably in seconds, the totalmixing of each batch for various settings of the handwheel relativethereto. A second dial Ill mounted on the handwheel indicates thecorrections to be made if the R. P. M. of the drum is varied.

With two-compartment drums, as herein shown, the mixing time will be theinterval of time elapsing between the time when the skip is fullyelevated and the discharge of that same batch from the secondcompartment of the drum.

18 it should, the mixing period of each of the two batches in the drum.

The present invention provides means by which the setting of the timinginstrumentallties associated with the cycle control advances or retardsthe completion of each mixing cycle but only. in an amount whichcompensates for the fact that two operations of the mixing cycle areinvolved in each setting of these cycle control instrumentalities.

Keyed or otherwise integrally secured to the sleeve I" is a hub III towhich is afiixed a shaft IN on which are Journalled the integral,planetary cluster gears I" and ill, the larger of which I" meshes with a.sun gear 2" keyed to the shaft H (see Figs. 4 and 15). The smallercluster gear I" meshes with a gear Ill mounted on the hub ill whichcarries the cam I which sets in operation the mixing control shaft 18through the follower arm I" and clutch shifter mechanism previouslydescribed. The gear ratios in the planetary gearing are such thatrotation of the sleeve III by a given amount and in a given directionwill rotate the hub m and cam m by The elevation of the skip occurs ata. predetermined time interval after the inauguration of the controlcycle: similarly the bell "I will ring in the first instance at apredetermined time interval after the inauguration of this controlcycle, and hence at a predetermined time interval after the elevation ofthe skip. Under proper operation, the control cycle is reinaugurated themoment the bell rings in'the first instance, and

' the ringing of the bell in the second instance will totalise thecomplete mixing time, as'may be indicated on the dial III, of theaforesaid batch.

Since the total elapsed time for a batch of concrete to pass through themixing drum includes the time when the succeeding batch is in the firstcompartment of the mixer, it follows that there. will be two runs ofthe, mixing control cycle during each mixing period. In other words, thetiming instrumentality which signals the completion of the mixing cycle,is set in operation twice during the total mixing period of a givenbatch. first to determine when the batch in the second compartment is tobe discharged,

and second, after the batch in the first compartment has beentransferred to the second compartment, to indicate when that batch is tobe discharged Any advance or retardation of the setting of the camsassociated with the cycle control shaft, which affects the time when themixing cycle commences, should advance or retard the setting of the camthat inaugurates the mixing cycle only one-half as much. Otherwise eachadjustment of the discharge or transfer time, which only affects thetime of operation on one batch, will be reflected disproportionately,

by increasing or decreasing by twice as much as only one-half as much inthe same direction. Since the sleeve I" is in turn locked to the plateill any adjustment by means of screw Ill of the setting of the camswhich terminate discharge and inaugurate transfer will also produce thesame corresponding adjustment of the commencement of the mixing controlcycle in the reduced ratio described. Similarly, any adjustment of camscontrolled by setscrew Ill will produce a similar efiect.

Thus with this arrangement, the completion of the mixing cycle is solelydependent upon the setting of the cams on the mixing control shaft II,and as previously mentioned their position may be adjusted by thehandwheel Ill, without affecting any of the functions of the cyclecontrol. The compensated advance or retarding of the time when themixing cycle commences does not affect the setting of the handwheel it,which determines that the originally specified total mixing period willelapse before discharge may be effected quite regardless of the adjust-Cycle control shaft latch As previously described, the cycle control 14is set in operation by the removal of the roller I" from the notch inthe cam I simultaneously with the movement of the clutch 18 intoengagement with the clutch disc 1s. When the cam l8 engages theinterrupter mechanism 9|, '3, it, etc., the clutch 10 is snapped out ofengagement, and the shaft It with its associated cams is free to rotate,since the roller I at this time is riding on the smooth portion of thecam I. The force required to compress the spring I", when clutch ii isdisengaged, is transmitted through the stronger spring I4, and exertspressure through the roller follower against the slope U of the cam 80,thereby tending to rotate the shaft when the clutch is disengaged.

The latch Ill, best illustrated in Fig. 4, has a dog tooth '2 arrangedto mesh with the teeth of the disc II when the latch is shiftedtransversely to the disc. The latter movement is effected by a tensionspring 2i: anchored to the housing of the box. A downwardly extendingpin on the lower arm of the shifter 8| engages an ward in the mannerjust described, until meshing occurs. This backward rotation, whiledesirable in providing latching action, is exiguous, insofar asre-engaging the clutch IS.

The latch 2!!! is supported by two sets of parallel links 2 which areupstanding from the bottom of the case I and between which the spring 2|2 extends.

The latch 2H1 also serves to prevent the shaft I4 being inadvertentlyrotated while the con trol is interrupted, which would otherwise destroythe proper time sequence between the operation of the cams.

The foregoing completes the description of the operating mechanisms inthe two control boxes and the correlation between their functions. Theenclosed construction surrounding these mechanisms provides suitableprotection for the class of service required, but the side plates may beeasily removed should it be necessary to repair or replace any of theparts. A window H5 in the front panel exposes the revolution counter I59and permits the same to be viewed. The drive-shaft 69 and associatedgearing, the control shafts I3 and I4, the stub shaft 69 with itsassociated chain and gears, are lubricated by the drip cup 2 I 6' andthe system of piping 2I6, best illustrated in Figs. 2 and 4, whichconstantly supplies lubricant by gravity to the ends of these shafts.Suitably disposed apertures in the sleeves and hubs on which the camsare mounted permit the lubricant flowing along the interior of the shaftto be metered at each revolution of the shaft and to drip down to thecam and follower surfaces.

The housing for the control mechanism is mounted on the frame, asillustrated in Fig.v 2, adjacent the operators platform, and the fluidcontrol valves are suspended from the underside of the box I5. The lowerextremity of the saddle 2H in which the control valves are mounted isyieldably anchored to the frame by a hook 2I8 which connects it to theframe of the machine, and permits the frame to weave under extreme roadconditions without stressing the control mechanisms.

The apparatus as heretofore described is suitable for practically allconcrete mixing work. However, some concrete specifications may requirea longer mixing period than can be obtained by the adjustment of thehandwheel I95 and associated mechanism shown in Fig. 4. To meet thiscontingency, the apparatus may be modified as shown in Figs. 17 and 18(wherein like elements carry the same reference characters as in theearlier figures), in which event the sleeve I94 mounted on the mixcontrol shaft I3 is made to rotate at a slower rate of speed than theshaft I3.

The sleeve I94 is split as at 220, and a sprocket .22I is rigidlyconnected to that portion 222 of the sleeve on which the aforesaidhandwheel I95 is mounted. A countershaft 223 adjustably mountto thesleeve :94 by sprockets zzrand'zza and 1 chain 229. Sprockets 225 and221 have acommon hub 230; and by providing twice as many teeth onsprocket 225 as 'on sprocket22l; thespe'ed of rota'- tion of sleeve I94may be reduced to one-half that of theshaft 13. In other words, theshaft 13 may make two complete revolutions while the sleeve I94 makesbut one revolution. I

It remains only to prevent thecam follower IGB'from dropping into thenotch in the-camlII,

which would otherwise upon completion of one revolution, disengage theclutch controlling the drive of the mix control shaft I3, untilthe notchhas passed the follower, and this is accomplished by providing a camplate 23I on the sleeve I94 in position to be engagedby the pin 232 onwhich the roller follower IE6 is mounted. The cam plate 23I is arrangedso that when the shaft I3 has completed one revolution,the follower I66is maintained in outward position b'y the plate 23I," but upontworevolutions of the shaft '13, the

plate 23I which is rotating at a differential speed relative to theshaftl3, is freed from the pin 232, and the roller I66 is permitted'todrop into the notch in the cam I1 I. Thi disengages the clutchcontrolling the shaft 13 and the roller I 66 locks the shaft againstfurther movement.

By selecting appropriately shaped cams 234 and I49 torelease thedischarge chute controllock and to effect the bell signal at the end ofthe mixing cycle,-these functions may be detended period of described.

In fact, the standard apparatus maybe as shown in Figs. 17 and 18, witha chain coupling replacing the chains 22!; and 229 and providing adirect, no speed change drive between the shaft I3 and the sleeve I94.If this is done, the pin 232 is removed, so that at no part of theadjustable range of the handwheel I will any engagement with the plate23I take place, and so that the mix control shaft will come to restexactly as shown in Figs. 1-16. A replacement cam is substituted for thecam 234, permitting operation of the control lever for the dischargechute at the proper time in the shorter cycle which is normallyemployed.

If the longer cycle is to be employed, utilizing the apparatus of Figs.1'7 and 18, the dial strip'2lll shown in Fig. 5 should be replaced by adial strip suitably graduated for the time intervals which would beinvolved in this cycle.

Summary of normal operation I A complete normal cycle of operation ofthe control mechanism may be briefly summarized as follows:

1. Lever 81 is manually pushed inwardly to cause engagement of clutchIS, with consequent rotation of shaft I4, and simultaneously there.-with, or approximately so, lever H5 is also manually pushed inwardly sothat movement of the discharge chute 38 to discharge position isimmediately inaugurated.

2. Cam H0 starts movement of the discharge chute to non-dischargeposition, and more or less simultaneously therewith, cam H6 causestransfer door I9 to begin movement to open position.

3. Cam 88 interrupts cycle, unless lever 81 is held inwardly byoperator. If cycle is interbrake is then manipulated by the operator tocontrol lowering of the skip.

7. Cam it! causes engagement of clutch I1, thereby initiating rotationof shaft 13 and starting timing of mixing period.

8. At one complete revolution of shaft 14,

roller I" moves into recess ill of disc I, disengaging clutch I! andstopping shaft ll.

9. Cam in causes rod I" to protrude, thereby preventing associated leverIll from being manipulated prior to the requisite amount of mixins.

10. Cam I 3i closes the water valve.

11. Cam I rings bell iii, and simultaneously therewith or slightly inadvance thereof as desired, cam I52 shifts plunger i" to unlockdischarge chute control lever III. This lever is then pushed inwardly bythe operator to initiate movement of the discharge chute as described instep 1 above.

12. At one complete revolution of shaft II, (or two complete revolutionswith the modification of Figs. 17 and 18), the roller associated withdisc ill moves into the notch in said disc, whereby the clutch 11 isdisengaged and rotation of shaft I! is stopped. The final movement ofshaft II in its cycle may overlap the recommencement of a new cycle ofshaft H. since the latter normally commences simultaneously with step iiabove.

The invention having been described, what is claimed is:

1. In apparatus for correlating the functioning of a plurality ofoperating instrumentalities of a two-compartment concrete mixer,including one for timing the period of mixing, the combination of aplurality of cams mounted for adjustment relative to one another; meansfor moving said cams through an operating cycle, means operable bycertain of the cams during such cycle to control the functioning of saidmixer instrumentalities other than the one for timing the mixing period;means for adjusting the setting of such cams relative to one anotherwhereby their functioning may be varied as different mixer operatingconditions require; mechanism operable by another of the cams toinitiate a cycle of said timing instrumentality; and differentiallyoperating connections between said last named cam and the other forautomatically adjusting the former to a different degree than the latterwhen their setting is changed.

2. In apparatus for correlating the functioning of a plurality ofoperating instrumentalities of a two-compartment concrete mixer,including one operable through a plurality of cycles to time the mixingperiod of each batch, the combinationof a plurality of cams mounted foradjustment relative to one another; means for moving said cams throughan operating cycle; means operable by certain of the cams during suchcycle to control the functioning of said mixer instrumentalities otherthan the one for timing the mixing period; means for adjusting thesetting 20 of such cams relative to one another whereby the timing oftheir functioning may be varied as diii'erent mixer operating conditionsrequire; mechanism operable by another of the cams to initiate thecycles of said timing instrumentality; and reducing gear connectionsbetween said last named cam and the others for automatically adlustingthe former to a lesser degree than the latter when their setting ischanged.

3. In apparatus for correlating the functioning of a plurality ofoperating instrumentallties of a two-compartment concrete mixer,including one operable through two cycles to time the mix ing period ofeach batch, the combination of a plurality of cams mounted foradjustment relative to one another; means for moving said cams throughan operating cycle; means operable by certain of the cams during suchcycle to control the functioning of said mixer instrumentaiities otherthan the one for timing the mixing period; means for adjusting thesetting of such cams relative to one another whereby the timing of theirfunctioning may be varied as different mixer operating conditionsrequire; mechanism operable by another of thevcams to initiate thecycles of said timing instrumentality; and planetary gear connectionsbetween said last named cam and the others for automatically adjustingthe former to substantially one half the extent of the latter when theirsetting is changed.

4. In apparatus for correlating the function- .ing of a plurality ofoperating instrumentalities of a plural compartment concrete mixer,including one operable through a plurality of cycles to time the mixingperiod of each batch, the combination of a plurality of cam-carryingelements mounted for adjustment relative to one another whereby tochange the'timing of the functioning of their respective cams, whichchange afiects the time of commencement of the mixing period; means forso adjusting said cam elements; means for moving the. elements throughan operating cycle; means operable by the cams thereof during such cycleto control the functioning of said mixer instrumentalities other thanthe one for timing the mixing period; a cam mounted for cyclic-movementwith one of said elements, and adjustment relative thereto to change itstiming; means operable by such cam to control initiation of the cyclesof said timing instrumentality; and motion reducing connections betweenthe last named cam and its associated cam-carrying element, operablethrough adjustment of the elements relative to one another toautomatically change the setting of such cam to a lesser degree.

5. In cyclically operable apparatus for controlling the functioning of aplurality of concrete mixer instrumentalities, the combination of aplurality or sequentially functioning cams; means for operating saidcams in a cycle; fluid pressure actuated means for controlling thefunctioning of the various mixer instrumentalities; valves forcontrolling said fluid pressure means; mechanisms operable by said camsfor actuating said valves; manually operable means for actuating thevalves independently of said cam operated mechanisms; and yieldabledevices included in said mechanisms, whereby actuation of the valves bythe cams may be prevented through manipulation ofsaid manually operablemeans.

6. In cyclically operable apparatus for controlling the functioning of aplurality of concrete mixer in'strumentalities, the combination of aplurality of sequentially functioning cams; means for

